I'm genuinely curious how GOG managed to nab games like Mortal Kombat 4, Metal Gear Solid 1 and 2, Silent Hill 4, Bladerunner, Stranglehold, the Ultima franchise, The older Might and Magic titles, the Gold box and other classic D&D games. Hell, even Diablo, Warcraft 1 and 2 which aren't even on Battlenet, among many many others, and keep them this long as digital exclusives.

I'm just wondering if behind the scenes GOG is doing some exclusive bids on older games. And before anyone gets the wrong idea, I ain't mad if they are doing this. Not trying to draw any comparisons to them and EGS either. And I'm not hoping they go to other storefronts. If they do, that is fine, if they don't, that's cool too.

Just wondering how these games, which are pretty much major titles, only available digitally on GOG.

My guess is that at least part of those games are on GOG only due to lack of interest from current "owners" to publish them somewhere else. Not only due to technical difficulties, but also because they're not considered as "profitable enough" to be released on Steam etc. Guess that Warcraft 1-2 and Diablo 1 were considered by Blizzard as "we don't care anymore, since we're not planning to make something with those (remaster/etc)".

It's just my assumption though. I'm also surprised that some games which look like a perfect candidate to travel on Steam due to "big demand" (like Jazz Jackrabbit series) are still not there.

Obviously, the details are different for each game and you are not going to get an official answer.

But as far as I know there are no deals that restrict the release of games that are "exclusive on GOG". (With the possible exception of Diablo and Warcraft 1 + 2, I have no idea how the deal between Gog and Blizzard is set up but the wording of the news posts when these were released made it sound like there was more collaboration between Gog and Blizzard than usual)

For most games there are a number of hurdles before it can be released, that make games effective exclusives simply because only GOG is willing to put the work in to overcome them.
These hurdles include, but are not limited to:
- Figuring out who can give Gog the permission to release the game in question. Companies that own the IP go out of business, and the rights are bought by another company who, in turn, went out of business years ago. Figuring out who to talk to and then get a hold of these companies and sometimes individuals can be extremely complicated.
- Getting the game to run on a modern computer. Sometimes that's easy (with Dosbox), sometimes you need the Sourcecode to fix a 20 year old bug, that only manifests if you have more than 2GB of memory (which was just impossible in 1995)
- providing continous technical support for the game and updating it in case future hardware breaks it again

Changes made by Gog to the game may be owned by Gog or they will be provided to the publisher (who then, theoretically, can release the game on other platforms).

It's unlikely that GOG has the money to pay for exclusives. Most likely, they agree on exclusivity (timed or not) in exchange for doing all the technical support themselves.

As for Jazz Jackrabbit, I think that Epic isn't so keen nowadays on releasing stuff on Steam.

More likely the legal work, because in many cases the technical work is done by third party projects, like Blade Runner and ScummVM.

There have been of course some rumours from time to time, that companies would pay some money to these projects to do the work. I seem to recall at least some rumour about ScummVM and DotEmu.

The only thing I can find to cover that is a mention on ScummVM forums:
"The ScummVM team, in close collaboration with Nayma soft (the legal rights owner) and DotEmu, is happy to announce support for Tony Tough in our development branch. The title is available for purchase from DotEmu."

http://forums.scummvm.org/viewtopic.php?t=11900

GOG could be "in close collaboration" with some parties as well, naturally no one outside knows what kind of agreements there are about money and exclusivity.

Yes, most of the time